Single lens glasses are widely used for sports and industry, such single lens glasses closely cover the two eyes of a user. The conventional mold for producing prior art single focus single lens glasses is shown in FIG. 7. The conventional mold comprises a male mold 11 and a female mold 12, each respectively having a different radius for use in a plastic injecting process, where plastic is injected into the space between the molds. The single lens glasses have a single central point 13 where the lens is the thickest.
These type of single lens glasses are used for sports and in industry and function to protect human eyes, but it easily makes the user's eyes tired if such glasses are worn for a long period of time. Most of the people who use these glasses have experienced the problem. The problem is caused by the fact that the lens only has a single focal axis which is centrally located, instead of two focal axes displaced from one another by a distance corresponding to the distance between the pupils of a person's two eyes, normally about 65-68 mm. That is the reason why the single lens glasses cannot enable human eyes to still feel comfortable after wearing such glasses for a long period of time.